They will recognize the need long before they act on it. And when they act on it, it will be on an offering built to their specifications, with data connections to other enterprise systems that they have millions invested in.
And most of the initial mobile rollout for enterprise will be shoddy half-assed stabs in the dark by the same enterprise vendors they already have, that are neither well designed, nor disruptive, nor will they deliver on the promise of mobile particularly well.
Even now in slow industries like ECAD and MCAD I see AutoDesk, Dassault Solidworks, and Altium working on more collaborative software like their PDMs (like Solidworks Vault) and more mobile applications to view and annotate CAD models. AutoDesk especially has exploded with many web and mobile apps ranging from 3D scanning to editing and 3d printing.
I don't think 2013 is the year but it is certainly only the beginning.
So while the enterprise market isn't growing, the mobile enterprise market is.